MJExplorer manifest prebuild fails open: a missing Open App's screens look like a build that worked

Filed from **Caliber** (`MemberJunction/bizapps-caliber`), an Open App on MJ.

**Pinned against:** MJ 5.51.0 · **Severity:** small change, prevents a silent whole-feature outage

The MJExplorer template's manifest prebuild ends in a shell fallback:

```
mj codegen manifest --exclude-packages @memberjunction --output ./src/app/generated/class-registrations-manifest.ts \
|| echo 'Warning: mj codegen manifest not available, using existing manifest'
```

When the manifest step fails for any reason — CLI not installed in that environment, an unresolvable
dependency, a config it cannot read — the build continues and links the **stale committed manifest**.
For a host with installed Open Apps that is not a degraded build, it is a wrong one: the managed
`Open App client bootstrap` block is what makes an installed app's client classes register, so the
symptom is that the app's screens are simply absent, with a green build and no error anywhere. A
warning on stdout does not survive CI log volume, and nothing downstream re-checks.

This bites specifically because the block is *generated*, not authored — there is no file in the host
repo whose absence a reviewer would notice.

**The ask:** drop the `|| echo` (let a failed manifest fail the build), or keep the fallback but exit
non-zero when the existing manifest predates the current `dynamicPackages.client` list. Either makes
the failure loud at the moment it is cheap to fix.

**What Caliber ships today:** `apps/MJExplorer` runs the same command with **no** fallback, wired to
both `prebuild` and `prestart`, and `smoke/config/client-bootstrap.test.mjs` asserts the scripts
contain no `||` and that the generated manifest still carries both the bootstrap block and the two
dashboard classes MJ's class factory resolves. That protects our repo; it does nothing for a host
using the template, which is why the ask stands.

---

Locate the MJExplorer template's manifest prebuild command and compare it with the no-fallback scripts in apps/MJExplorer. Run smoke/config/client-bootstrap.test.mjs to review the existing checks for the scripts and generated manifest. Done means a manifest-generation failure is visible to the host build, while the bootstrap block and both dashboard classes remain present when generation succeeds.

Written by the indexing model from the issue text.